John Calvin Commentary Deuteronomy 2:4

"And command thou the people, saying, Ye are to pass through the border of your brethren the children of Esau, that dwell in Seir; and they will be afraid of you: take ye good heed unto yourselves therefore;" — Deuteronomy 2:4 (ASV)

And they shall be afraid of you. This temptation was all the more provoking when they heard not only that the embassy would be futile, but also that even if Edom were to receive them with injustice and hostility, they were still to abstain from violence and arms. For one might reason that if they presented their request in a friendly manner, they would have a legitimate cause for war if Edom rejected their demands. But this further condition—that they were to do nothing against those who refused to let them pass quietly through their land—might seem completely intolerable.

Therefore, however, it becomes more apparent how the Israelites were gradually, and by various kinds of chastisement, subdued to obedience; otherwise, they would have fiercely and petulantly exclaimed that God had dealt with them unkindly, since their condition would then be worse than what the universal law of nations allowed. In this matter, then, their wanderings for thirty-eight years had much efficacy in bringing them back to the right way.